Antimicrobial resistance of bacterial pathogens isolated from the infections of post maxillofacial surgery

Inappropriate antibiotic prescriptions contributed to a global issue of antimicrobial resistance. This study aimed to assess the prevalence of bacterial pathogens and antimicrobial resistance isolated from maxillofacial infections (MIs). Two hundred and twenty-two patients with different MIs were included in this study. Swab samples were taken from the site of infections. Samples were cultured, and isolated bacteria were identified using various biochemical tests. Antimicrobial resistance patterns of isolates were assessed by the disk diffusion method. The mean age of the patients was 50.8 years. The male-to-female ratio was 127/95 (P<0.05). Smoking and alcohol consumption were found in 60.36% and 37.38% of patients, respectively. Most patients had a ≤1-week infection duration (P<0.05). Abscess lesion was the most predominant infection type (P<0.05). The prevalence of aerobic bacteria among abscess, pus localization, and deep facial infections was 59.33%, 64.28%, and 46.66%, respectively. The prevalence of anaerobic bacteria among abscess, pus localization, and deep facial infections was 40.66%, 23.80%, and 53.33%, respectively. Staphylococcus aureus (10.36%) and Prevotella buccalis (8.55%) had the uppermost distribution amongst all examined samples. Isolated bacteria exhibited the uppermost resistance rate toward penicillin (65.76%), tetracycline (61.26%), gentamicin (58.10%), and ampicillin (57.65%) antimicrobials. The lowest resistance rate was obtained for linezolid (25.67%), ceftriaxone (31.08%), and azithromycin (31.08%) antimicrobials. Linezolid, ceftriaxone, and azithromycin had effective antimicrobial activities toward bacteria isolated from MIs. Therefore, cautious antibiotic prescription might decrease the prevalence of antimicrobial resistance in dental and maxillofacial infections.


INTRODUCTION
Maxillofacial infections (MIs) are commonly attributed to the face and oral cavity [1]. Given the important anatomical position of the maxillofacial region, infections of this part may expand to other sites, including the respiratory system, brain, and mediastinum, and subsequent septicemia and even death may occur [2]. MIs are primarily self-limiting and can be treated quickly. However, there is a risk of death from airway obstruction and even infection spread [3,4].
Treatment of most MI cases requires an antimicrobial prescription. However, most aerobic and anaerobic bacteria responsible for MI exhibit a high resistance rate toward common antimicrobials [11]. The high antibiotic resistance rate of aerobic and anaerobic bacteria responsible for MI cases has been reported toward aminoglycosides, tetracyclines, penicillins, cephalosporins, quinolones, and other important classes of antimicrobials JOURNAL of MEDICINE and LIFE [12][13][14]. Thus, assessing MIs etiologic agent antimicrobial resistance can help identify the best antibiotics to treat and control the infection.
Given the high importance of MIs as common and complicated bacterial infections with the emergence of antimicrobial resistance, existing research was conducted to assess the prevalence and antimicrobial resistance of aerobic and anaerobic bacteria isolated from different types of MIs.

Study population, inclusion, and exclusion criteria
A total of 300 patients were included in the study from October 2019 to October 2020.
Inclusion criteria: patients with bacterial infections of odontogenic origin, including dentoalveolar abscess, those with deep fascial space spreading infections, and others with infections causing localization of pus in the head and neck, were included in the study.
Exclusion criteria: patients with viral and fungal infections, infected cysts, neoplastic lesions, and those without known infections were excluded from the study. Additionally, patients with antibiotic therapy (over the past 30 days) and who used antiseptic mouth rinses (over the past 24h) were excluded from the survey. Pregnant women, patients with liver, gastrointestinal, and kidney disease, and those with positive Covid-19 and HIV tests were also excluded.

Samples
Aspiration sites were cleaned with alcohol (Merck, Germany). Saliva was continuously aspirated during the sampling. A separate sterile needle was used for pus aspiration from each patient. If aspiration was unsuccessful, a separate sterile swab was used for pus or exudate collection. Samples were transferred to the laboratory using the thioglycollate broth (Merck, Germany) media. Geographical information of the targeted population was recorded accurately.

Bacterial isolation and identification
All samples were separately cultured on the blood agar media (Merck, Germany) for aerobic incubation, chocolate agar (Merck, Germany) for microaerophilic incubation, and anaerobic blood agar (Merck, Germany) for anaerobic incubation. The blood agar media was prepared using the blood agar base (Oxoid, UK) with 5% defibrinated sheep blood. The anaerobic blood agar media was prepared using the fastidious anaerobe agar (Oxoid, UK) with 5% defibrinated sheep blood. All media were incubated at 37ºC. All isolates were subjected to Gram-staining. Isolates grown on the blood agar and chocolate agar were Gram-stained after 24h of growth in air and CO 2 , respectively. Isolates grown on the anaerobic blood agar were Gram-stained after 48h. Gram-negative and Gram-positive bacteria were tested using various biochemical tests according to the Analytical Profile Index (API) system. Gram-negative bacillus bacteria were identified using the API 20E [15]. The catalase production test was used for Gram-positive coccoid bacteria. All catalase-negative bacteria were tested for the hemolytic reaction, and growth in the media contained 6.5% NaCl. Catalase-positive bacteria were tested for coagulase production, resistance to Novobiocin, and growth on the mannitol salt agar (MSA, Merck, Germany). Anaerobic bacteria were identified using the AP120A procedures [16]. Anaerobic culture was provided using the anaerobic jar (Oxoid, UK) and MART system (Lichtenvoorde, The Netherlands, 80% N 2 , 10% O 2 , and 10% CO 2 ) [17][18][19].
Isolates displayed a high antibiotic resistance rate toward penicillin, tetracycline, gentamicin, and ampicillin antimicrobials. Unauthorized prescription of antimicrobials, self-treatment with antimicrobials, and indiscriminate use of disinfectants are likely explanations for the prevalence of antimicrobial resistance in the present survey. Linezolid, ceftriaxone, and azithromycin prescription may cause better therapeutic effects on maxillofacial infections. Similarly, a high resistance rate toward penicillin, tetracycline, gentamicin, and ampicillin antimicrobials was reported in the United States [51], Australia [52], and the United Kingdom [53]. Kong and Kim (2019) [54] stated that the S. aureus, S. viridans, K. pneumoniae, and E. fecalis bacteria displayed the uppermost resistance rate against ampicillin, ciprofloxacin, clindamycin, erythromycin, gentamicin, penicillin, and tetracycline antimicrobials [55]. Habib et al. (2019) [56] stated that Staphylococcus spp., Streptococcus spp., and Klebsiella spp. isolates of odontogenic infections had a high resistance toward amoxicillin and metronidazole (80-100%). A Chinese survey [57] described boosting resistance rate toward ampicillin (100%) and penicillin (100%) antimicrobials. Possible reasons for antibiotic resistance differences reported in various studies include differences in antibiotic availability, antibiotic prices, over-the-counter antibiotic sales, and antibiotic prescribing procedures. Precise prescriptions based on laboratory results can diminish the risk of antimicrobial resistance among maxillofacial pathogens.
There is no determined document about the exact origin of isolated bacteria. However, the role of food as a vector for these bacteria and also changes in the microflora of the oral cavity are more prone than other reasons [58,59]. We suggest other authors assess the originality of oral infections and the full genome sequencing of bacterial isolates to assess their genetic similarity.

CONCLUSIONS
The main achievement of this report was the assessment of antimicrobial resistance of bacteria isolated from infections of post maxillofacial surgery in order to identify the best treatment option and the main distribution of bacterial pathogens in these areas. In conclusion, S. aureus, S. pyogenes, S. viridans, K. pneumonia, P. buccalis, Peptostreptococcus spp., and P. gingivalis were the predominant causes of maxillofacial infections in Iraq. Rendering the disk diffusion findings, linezolid, ceftriaxone, and azithromycin prescription may cause better results in treating maxillofacial infections. Establishing preventive rules in prescribing antibiotics and accurately identifying the main causes of infection in these areas can prevent the spread of antibiotic-resistant strains in post maxillofacial surgery infections. However, several multifactorial surveys should be performed to address more aspects of the antimicrobial resistance bacteria in MIs.